A liquid cooling system and a control method thereof are disclosed. The liquid cooling system includes at least two second-level liquid circulation loops and a cooling control apparatus. One second-level liquid circulation loop is provided with a circulating pump configured to control a liquid flow and a sensing apparatus configured to acquire liquid sample data. The control method includes acquiring liquid sample data using sensing apparatuses of a liquid cooling system; implementing sharing of the liquid sample data of the sensing apparatuses using a cooling control apparatus, performing analytical processing on the liquid sample data, and calculating a circulation regulation value of circulating pumps; and sending the circulation regulation value to the circulating pumps using the cooling control apparatus, such that the circulating pumps run according to the circulation regulation value.